1. Field of the Invention
The present invention relates to testing the fluid absorption rate of soil. More particularly, the present invention is directed to soil testing apparatus and particularly to apparatus which while unattended will provide a permanent record of the rate of absorption of fluid by soil or the rate of fluid infiltration into a bore hole. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.
2. Description of the Prior Art
The water absorption or percolation characteristics of soil are of critical importance in determining whether a proposed land use is appropriate. Thus, by way of example only, one of the primary responsibilities of field environmental health workers is evaluation of individual sewage disposal system sites. This evaluation commonly includes a "percolation test" which provides a measure of the soil's ability to absorb liquid run-off from a septic tank. Thus, the results of the percolation test will determine the square footage of absorptive soil necessary to handle a given output from a home or business.
At present, in order to perform a soil percolation test, an evacuation of a given diameter is made down to the level at which the contemplated absorption is to occur. That excavation is filled with water and, after a certain amount of time has passed for some level of equilibrium or saturation to have occurred, the hole is refilled and a mark placed at a high water point. This is usually accomplished by either placing a cross bar with hanging member above the hole or by inserting a marker in the side wall of the hole. The time when the cross bar or marker is put in place is recorded. Thereafter, using preset periods of time, a series of measurements of the water level in the hole are taken and manually recorded. A conventional, manual percolation test of the type being described requires the presence of an observer for periods of up to two hours. Further, the information of interest is obtained by making a comparison between two separated points; i.e., the water level at the time the measurement is taken and either the previous or the initial level where the marker was placed; and these points are customarily a significant distance below the surface level and thus must be viewed at a substantial angle. This problem of looking at two points at the same time combined with the extreme perspective makes accurate measurements difficult. The necessity of making the measurements at set uniform time intervals further contributes to the inaccuracy of the prior art testing procedure since distractions, conversation, boredom, etc. often result in the time intervals between successive measurements varying. From a purely economic viewpoint, of course, the requirement that an individual spend up to two hours doing so little; i.e., making a few measurements as the water is absorbed into the soil; is highly inefficient. Attempts to enhance efficiency, and thereby reduce costs of an individual test, by assigning the test personnel to other tasks between the successive measurements only contributes to the inaccuracies of the measurement. Thus, in order to record the soil percolation characteristics with the required accuracy, the test site needs continual supervision.
Apparatus for use in performing soil percolation tests is well known in the art. Examples of such prior art apparatus are found in U.S. Pat. Nos. 3,926,143, 3,945,247, 4,099,406 and 4,182,157. The prior art soil percolation testers, while they avoid the need for manually placing markers in the excavation and making comparative measurements down in the hole, are nevertheless plagued by one or more inherent deficiencies. The most common of these deficiencies is the requirement for continual operator supervision if the desired information is to be accurately recorded. A further common deficiency resides in the relative complexity of the devices which often contributes to set-up problems and/or transportation difficulties. An additional deficiency, incident to the comparatively harsh treatment to which such apparatus is often subjected, results from a lack of modular construction which prevents damaged or consumed components from being discarded and replaced by new components.